The present invention relates generally to well tools of the type used to set downhole devices in a well bore and, specifically, to a wireline setting tool which is hydraulically actuated.
Various types of wireline setting tools are known in the art for setting downhole devices in a well bore. Such setting tools are engaged with the device to be set at the well surface and lowered to the desired setting depth within the well bore on a wireline or cable. Wireline setting tools have, in the past, generally utilized an explosive charge or bomb which was detonated by an electrical signal from the well surface and passed through the wireline to the firing chamber of the setting tool. The gases generated by ignition of the charge were used to compress a fluid such as oil, which, in turn, was used to drive a piston member. In certain of the prior art devices, the piston member was connected through a cross-link to an outer sleeve member which was disposed about an inner cooperating tubular member. Upon actuation of the charge, the outer sleeve and cooperating inner tubular member moved in opposite relative directions to effect the setting of a suitably engaged device such as a bridge plug, packer, or the like in the well bore.
There are many disadvantages inherent in the use of a setting tool which is actuated by an explosive charge. Explosives are dangerous to handle and difficult to store and maintain on the job site. Special permits and licenses are often required to comply with State and local safety regulations. Another problem associated with the use of explosive actuation is the necessity of providing a controlled, gradual setting action on the device to be set. Certain of the prior setting tools have included an orifice in the body of the tool through which oil is forced as detonation occurs to thereby slow the setting action on the device being set. Also, explosive charges which are "slow burning" are employed in order to lessen the undesirable effects of a sudden explosion. The use of an explosive charge also requires that the firing chamber of the tool be cleaned regularly between uses thereby adding to the maintenance requirements of the tool.
There exists a need, therefore, for a wireline setting tool which provides a gradual controlled setting action for setting downhole devices in a well bore.
There exists a need for such a device which does not require explosives and which can be reused without the attendant cleanup of an explosive actuated tool.